A semiconductor device includes an active region on a substrate, a device isolation film on the substrate to define the active region, a gate trench including a first portion in the active region and a second portion in the device isolation film, a gate electrode including a first gate embedded in the first portion of the gate trench and a second gate embedded in the second portion of the gate trench, a first gate capping pattern on the first gate and filling the first portion of the gate trench, and a second gate capping pattern on the second gate and filling the second portion of the gate trench, an upper surface of the first gate being higher than an upper surface of the second gate, and the first gate capping pattern and the second gate capping pattern have different structures.